This invention relates to body fluid drainage devices and more particularly to thoracic drainage devices.
In thoracic drainage systems, a catheter is disposed within the pleural cavity of a patient and connected to a drainage collection container or bottle. In many cases, an initial amount of liquid is provided in the container and the catheter is connected to a drainage tube extending below the level of the liquid to provide a liquid seal. This liquid seal prevents the cavity from being in direct fluid communication with the atmosphere or a source of vacuum which may be used to assist in the draining of fluid from the cavity. One of the disadvantages of such an arrangement is that, should an air leak occur in either the cavity of the patient or in a tube connection between the cavity and the container, blood foam is generally produced that rises above the drainage liquid and tends to fill the interior of the container. Where a vacuum source is connected to the container for assisting the drainage fluid flow, the foam build-up is even more rapid. If allowed to fill the container, such foam may enter the vacuum source causing damage to it. Thus, a container filled with foam requires the connection of a new bottle even though the container could have held substantially more gas-free liquid. Because of the foam, such thoracic drainage devices require considerable monitoring to insure that foam does not accumulate such that it fills the container. Also, foam obscures the liquid level and it is more difficult to determine the actual amount of drainage liquid in the container when a significant amount of foam is present.